Tetramorium nazgul Hita, 2012

Hita Garcia, F. & B. L. Fisher, 2012, The ant genus Tetramorium Mayr (Hymenoptera: Formicidae) in the Malagasy region - taxonomic revision of the T. kelleri and T. tortuosum species groups., Zootaxa 3592, pp. 1-85 : 74-76

Tetramorium nazgul Hita Garcia & Fisher sp. n.

(Figs. 19, 20, 132, 133, 134, 142)

Holotype worker, MADAGASCAR, Toliara, Réserve Spéciale d'Ambohijanahary, Forêt d'Ankazotsihitafototra, 35.2 km 312° NW Ambaravaranala, 18.26667 S, 45.40667 E, 1050 m, montane rainforest, sifted litter (leaf mold, rotten wood), collection code BLF07020, 13.-17.I.2003 (B.L. Fisher, C. Griswold et al.) (CASENT: CASENT0028625). Paratypes, 31 workers with same data as holotype (BMNH: CASENT0028584; CASC: CASENT0028579; CASENT0028585; CASENT0028590; CASENT0028591; CASENT0028601; CASENT0028604; CASENT0028605; CASENT0028606; CASENT0028610; CASENT0028620; CASENT0028621; CASENT0028622; CASENT0028626; CASENT0028627; CASENT0028628; CASENT0028632; CASENT0028636; CASENT0028652; CASENT0028663; CASENT0028670; CASENT0028671; CASENT0028674; CASENT0028678; CASENT0028680; CASENT0028681; CASENT0028689; CASENT0028690; MCZ: CASENT0028595; MHNG: CASENT0028594; NHMB: CASENT0028592).

Diagnosis

The following character combination renders T. nazgul easily diagnosable within the T. smaug species complex: antennal scapes comparatively long (SI 89-92); propodeal spines very long (PSLI 39-43); anterodorsal and posterodorsal margins of petiolar node situated at about same height; first gastral tergite with numerous standing hairs; dark brown to black body colour.

Description

HL 0.95-1.06 (1.02); HW 0.85-0.98 (0.93); SL 0.79-0.89 (0.84); EL 0.21-0.24 (0.22); PH 0.48-0.56 (0.53); PW 0.67-0.75 (0.73); WL 1.23-1.39 (1.34); PSL 0.38-0.45 (0.42); PTL 0.31-0.36 (0.34); PTH 0.38-0.43 (0.41); PTW 0.26-0.31 (0.29); PPL 0.31-0.36 (0.33); PPH 0.38-0.42 (0.41); PPW 0.35-0.41 (0.39); CI 90-92 (91); SI 89-92 (90); OI 23-25 (24); DMI 54-57 (55); LMI 37-41 (39); PSLI 39-43 (41); PeNI 37-42 (40); LPeI 81-88 (84); DPeI 82-89 (86); PpNI 51-55 (54); LPpI 78-85 (81); DPpI 113-122 (118); PPI 127-140 (133) (12 measured).

Head distinctly longer than wide (CI 90-92); posterior head margin concave. Anterior clypeal margin medially impressed. Frontal carinae strongly developed, diverging posteriorly, and ending at corners of posterior head margin. Antennal scrobes developed, shallow and narrow, without defined ventral margins. Antennal scapes of moderate length, not reaching posterior head margin (SI 89-92). Eyes of moderate size (OI 23-25). Mesosomal outline in profile flat to weakly convex, moderately marginate from lateral to dorsal mesosoma; promesonotal suture and metanotal groove absent; mesosoma comparatively stout and high (LMI 37-41). Propodeal spines very long, spinose and acute (PSLI 39-43); propodeal lobes well-developed, triangular, and usually acute. Petiolar node in profile rectangular nodiform, approximately 1.1 to 1.2 times higher than long (LPeI 81-88), anterior and posterior faces approximately parallel, anterodorsal and posterodorsal margins situated at about same height, dorsum flat to weakly convex; node in dorsal view approximately 1.1 to 1.2 times longer than wide (DPeI 82-89). Postpetiole in profile globular, approximately 1.2 to 1.3 times higher than long (LPpI 78-85); in dorsa l view around 1.1 to 1.2 times wider than long (DPpI 113-122). Postpetiole in profile appearing approximately as voluminous as petiolar node, in dorsal view approximately 1.3 to 1.4 times wider than petiolar node (PPI 127-140). Mandibles striate; clypeus longitudinally rugose/rugulose, with three to eight rugae/rugulae, median ruga usually present and distinct, remaining rugae/rugulae variably developed, usually weaker than median ruga; cephalic dorsum between frontal carinae with 8 to 13 longit udinal rugae, most rugae running unbroken from posterior head margin to anterior clypeus, few rugae interrupted and with cross- meshes; scrobal area mostly unsculptured; lateral and ventral head longitudinally rugose to reticulate-rugose. Mesosoma laterally and dorsally mainly longitudinally rugose. Forecoxae with well-developed and conspicuous longitudinal rugae. Waist segments strongly rugose. Gaster unsculptured, smooth, and shining. Ground sculpture generally faint to absent everywhere on body. All dorsal surfaces of head, mesosoma, waist segments, and gaster with abundant, long, and fine standing hairs. Anterior edges of antennal scapes with suberect to er ect hairs. Body of uniform dark brown to black colour, often appendages of slightly lighter colour.

Notes

This new species is known from few specimens from Analalava and Zombitse, both tropical dry forests, and a high number of specimens from the type locality Ambohijanahary, which is a montane rainforest. The altitudinal range is 700 to 1100 m, and T. nazgul appears to be a leaf litter inhabitant.

Within the T. smaug species complex, it is easily separated from the three species T. latreillei, T. sabatra, and T. smaug which have extremely long and massively developed propodeal spines with a very broad base (PSLI 48-72), whereas the spines of T. nazgul are very long, but less massive and without such a broad base (PSLI 39-43). Tetramorium adamsi, which is only known from the area around Manongarivo, has a petiolar node shape with the posterodorsal margin situated higher than the anterodorsal, whereas in T. nazgul both margins are about the same height. The last species of the complex, T. marojejy, is also very unlikely to be confused with T. nazgul. The most obvious character is colouration (orange to light brown in T. marojejy versus dark brown to black in T. nazgul), but they also differ in antennal scape length and shape of the waist segments. Tetramorium nazgul has longer antennal scapes (SI 89-92), a relatively longer petiolar node (LPeI 81-88), and a higher and broader postpetiole (LPpI 78-85; DPpI 113-122) than T. marojejy (SI 79-85; LPeI 89-97; LPpI 88-95; DPpI 101-109).

Etymology

The species name “nazgul” is taken from J.R.R. Tolkien's "The Lord of the Rings" and refers to the evil ringwraiths who serve the main villain “Sauron”. The species epithet is an arbitrary combination of letters.

Material examined

MADAGASCAR: Fianarantsoa, Forêt d'Analalava, 29.6 km 280° W Ranohira, 22.59167 S, 45.12833 E, 700 m, tropical dry forest, 1.-5.II.2003 (B.L. Fisher, C. Griswold et al.); Toliara, Réserve Spéciale d'Ambohijanahary, Forêt d'Ankazotsihitafototra, 35.2 km 312° NW Ambaravaranala, 18.26667 S, 45.40667 E, 1050 m, montane rainforest, 13.-17.I.2003 (B.L. Fisher, C. Griswold et al.); Toliara, Réserve Spéciale d'Ambohijanahary, Forêt d'Ankazotsihitafototra, 34.6 km 314° NW Ambaravaranala, 18.26 S, 45.4183 E, 1100 m, montane rainforest, 16.I.2003 (B.L. Fisher, C. Griswold et al.); Toliara, Parc National de Zombitse, 19.8 km 84° E Sakaraha, 22.84333 S, 44.71 E, 770 m, tropical dry forest, 5.-9.II.2003 (B.L. Fisher, C. Griswold et al.).